The present invention generally relates to valves, and more particularly relates to a pressure valve for a reciprocating pump for conveying pressure fluid in slip-controlled hydraulic brake systems.
A pressure valve of this general kind is disclosed in DE 44 07 978 A1. The pressure valve described in this paper is part of a hydraulic pump which is used for conveying pressure fluid in hydraulic brake systems. In addition to the pressure valve, the hydraulic pump also has a suction valve and a pump piston. The function of the hydraulic pump consists of conveying by piston action the brake fluid into the brake circuit when required. Pressure and suction valve are controlled by pressure. The stroke movement of the pump piston is generally generated by a cam on the drive shaft of an electric motor.
The pressure valve as defined in this state of the art, is threaded into the pump housing by a thrust piece with screw connection (cf. FIG. 2 as well as column 4, lines 17 to 21). The connection of the valve seating and thrust piece or valve cover is by way of a pliable seal (e.g. by caulking). This known form of design means that the pressure valve has to be manufactured by cutting process such as turning or milling. This means not only high manufacturing costs and tolerance requirements but also the disadvantage with components manufactured by metal-cutting, especially valves manufactured by metal-cutting, that shavings can get into the brake circuit which can restrict the function of the brake system and therefore the vehicle""s safety. Another disadvantage of the known pressure valve is that the screw connection of the pressure valve to the pump housing can be altered after installation meaning that manipulation is possible to the brake system by unauthorized persons.
The object of the present invention is to overcome the disadvantages of the state of the art and in particular to create a valve or pressure valve which is economical to manufacture, easy to install and particularly safe with regard to function.
This object is achieved by the invention of a pressure valve of the type named initially wherein the valve seat and/or the valve cover body are manufactured by non-cutting means. Preferred means of manufacture of the valve seat body and/or the valve cover body of the pressure valve are forming, reforming, punching, stamping and similar.
In a preferred embodiment of the present invention, the pressure valve is caulked into the pump housing. This type of fastening of the pressure valve provides a connection of the pressure valve with the housing which is safe against manipulation and pressure-resistant. In connection with a pressure valve with individual parts that have been manufactured by non-cutting means, this type of fastening offers a distinct advantage because caulking the pressure valve is also possible even if the valve cover, for example, has no thread for fastening into the pump housing or the valve block.
A preferred embodiment of the present invention shows the pressure valve as an autonomous installation subassembly suitable for handling. This has the advantage that it simplifies the installation of the pressure valve in a hydraulic pump and allows the pressure valve to be tested externally and separately prior to installation.
According to a possible embodiment, an adhesive joint is provided for the connection of the valve seat body and the valve cover body. The adhesive used is preferably a micro-encapsulated adhesive which does not have to be resistant to brake fluid because the connection of the valve seat body and the valve cover body is only necessary as an installation aid and during a test phase prior to installation.
According to another embodiment the pressure valve has a connecting device for connecting the valve seat body to the valve cover body. This connecting device is preferably in the form of a spring cup in which the spring is guided, wherein the spring cup preferably has at least one opening for the connection of the valve interior with a pressure fluid consumer.
A further preferred embodiment of the present invention has a self-locking connection between the valve seat body and the valve cover body. This is preferably realized by contacting angled surfaces.
The valve seat body and/or the valve cover body should preferably have at least one opening for the connection of the valve interior with a pressure fluid consumer. A particular advantage can be achieved by the valve seat body and/or the valve cover body having a further opening for controlling the resulting ball force.